Split-window CMP polishing pad and preparation method thereof

ABSTRACT

A preparation method of a split-window CMP polishing pad includes engraving a groove and a window in a backing, attaching the backing with a substrate through an adhesive, punching a hole in the substrate corresponding to the window through a substrate punching mold, forming window support blocks, punching an original window material through a punching machine and a window punching mold, obtaining a formed window material, coating another adhesive on the window support blocks, placing the formed window material into the window portion, and attaching the formed window material to the window support blocks. Compared with the sliced integrated-window, for the split-window provided by the present invention, the materials do not affect each other during the manufacturing process, so that the problem of uneven density distribution of the backing after curing can be solved, and the fluctuation of the tensile strength caused by uneven temperature is reduced.

CROSS REFERENCE OF RELATED APPLICATION

The present invention claims priority under 35 U.S.C. 119(a-d) to CN 201810877758.1, filed Aug. 3, 2018.

BACKGROUND OF THE PRESENT INVENTION Field of Invention

The present invention relates to the field of chemical mechanical polishing (CMP), and more particularly to a split-window CMP polishing pad and a preparation method thereof.

Description of Related Arts

CMP refers to chemical mechanical polishing. It basic principle is as follows. A rotated wafer to be polished is pressed on an elastic polishing pad rotating in a same direction with the rotated wafer, and the polishing slurry continuously flows between the wafer and a bottom plate; the upper and lower plates are reversely rotated at high speed, the reaction product on the surface of the wafer to be polished is continuously peeled off, the new polishing slurry is replenished, and the reaction product is taken away with the polishing slurry; the newly exposed surface of the wafer undergoes a chemical reaction, and the product is peeled off again and recycled, so that a super-precision surface is formed under the combined action of the substrate, abrasive particles and chemical reactants. As a consumable of the CMP process, the CMP polishing pad requires a transparent window for counting and positioning during use to precisely control the thickness of the polishing. A complete polishing pad comprises a backing, an adhesive and a substrate from top to bottom, wherein the backing is the part that is in contact with the wafer and mainly for grinding and polishing; the adhesive is adapted for bonding the backing with the substrate; and the substrate plays a support role. In order to ensure that the polishing liquid has a sufficient action time on the backing, a groove is usually engraved on the backing to store the polishing liquid; and at the same time, voids of the backing itself also store the polishing liquid and the abrasive particles, increasing the contact time and area of the abrasive particles with the wafer. Currently common on the market is a sliced integrated-window polishing pad produced by Dow, USA.

The sliced integrated-window is the main product of the Dow, USA. Its preparation method includes placing a pre-formed columnar window structure into a columnar mold and fixing, injecting a prepared polyurethane into the mold, and slicing an integrally formed columnar backing into a plurality of sheets after a whole is cured, so that the sliced integrated-window is formed. For the sliced integrated-window, when the backing is cured, temperature unevenness may occur, so that the local properties of the cured backing may be different. Moreover, uneven temperature affects the degree of cross-linking, which is manifested as fluctuations in tensile strength; the prepolymer of the mixed filler has a large viscosity and poor fluidity, only can slowly flow in the columnar mold, and the density after curing is not uniform, thereby generating a large amount of substandard waste; the uneven density will also affect the storage of the polishing liquid during the use of the backing, thereby affecting the polishing efficiency and the degree of flattening; the integrally formed columnar window is unstable in the mold, and there is also a window offset, which affects the infrared penetration window when counting.

SUMMARY OF THE PRESENT INVENTION

An object of the present invention is to provide a split-window CMP (chemical mechanical polishing) polishing pad and a preparation method thereof, both of which solve problems that a sliced integrated-window backing has uneven temperature during curing, which causes fluctuation of a tensile strength of the backing, and a density of the backing is not uniform and a scrap rate thereof is high after curing.

The present invention provides technical solutions as follows.

A preparation method of a split-window CMP (chemical mechanical polishing) polishing pad comprises steps of:

(S1) preparing a backing and engraving a groove on the backing;

(S2) preparing a substrate and coating a layer of first adhesive on a bottom of the substrate;

(S3) engraving a window portion on the backing engraved with the groove for accommodating a formed window material, wherein the window portion defines a window;

(S4) attaching the backing engraved with the window portion to the substrate coated with the layer of the first adhesive through a layer of second adhesive, forming a hole in the substrate corresponding to the window of the backing by punching through a substrate punching mold, and simultaneously forming two window support blocks at two sides of a bottom of the window portion, respectively, wherein the layer of first adhesive and the layer of second adhesive are respectively coated on the bottom and a top of the substrate;

(S5) punching an original window material through a punching machine and a window punching mold, and obtaining the formed window material;

(S6) coating a layer of primer on the two window support blocks; and

(S7) placing the formed window material into the window portion, attaching the formed window material to the window support blocks, and obtaining the CMP polishing pad.

Preferably, the window portion is oval with a long side in a range of 35 to 41 mm, an arc radius in a range of 8.6 to 10.6 mm, and a distance between a center of the window portion and a center of the backing in a range of 98.5 to 104.5 mm.

Preferably, the window portion has the long side of 38 mm, the arc radius of 9.5 mm, and the distance between the center of the window portion and the center of the backing of 101.5 mm.

Preferably, the substrate punching mold is oval, wherein a diameter of the hole is 2.7-3.3 mm smaller than a window size of the window portion.

Preferably, a size of the window punching mold is as same as that of the window portion.

Preferably, the primer is Primer 94.

A CMP (chemical mechanical polishing) polishing pad comprises a backing, a substrate, a first adhesive and a second adhesive, wherein: multiple grooves are provided on the backing, the backing comprises a window portion which defines a window, the substrate has a hole, a window material is accommodated within the window portion, and two window support blocks are respectively located at two sides of a bottom of the window portion.

Preferably, both the window and the hole have a same hole center, and a diameter of the hole is smaller than that of the window.

Preferably, the diameter of the hole is 2.7-3.3 mm smaller than that of the window.

Preferably, the two window support blocks are centrally symmetrically distributed to each other relatively to the window and the hole.

Compared with the prior art, the present invention has some beneficially effects as follows.

(1) Compared with the production method of the integrated-window backing, the backing and the window material of the present invention are separately manufactured, and the materials do not affect each other during the manufacturing process, so that the problem of uneven density distribution of the backing after curing can be solved, and the fluctuation of the tensile strength caused by uneven temperature is reduced.

(2) If the positioning error of the integrated-window material occurs, the entire batch of backing windows will be offset, resulting in the scrapping of the entire batch of materials; and the present invention adopts the split-window and processes one backing with a window once during the manufacturing process, if there is a window offset, only one backing will be scrapped and the entire batch of materials will not be scrapped, which can effectively reduce the scrap rate.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a location diagram of a window of a CMP polishing pad provided by the present invention.

FIG. 2 shows a shape of the window of the CMP polishing pad provided by the present invention.

FIG. 3 is a side view of the CMP polishing pad provided by the present invention.

FIG. 4 is a tensile strength fluctuation comparison chart of a split-window backing provided by the present invention and an integrated-window backing.

FIG. 5 is a density fluctuation comparison chart of the split-window backing provided by the present invention and the integrated-window backing.

FIG. 6 is a scrap rate comparison chart of the split-window backing provided by the present invention and the integrated-window backing.

In the drawings, 1: backing; 2: window portion; 3: second adhesive; 4: substrate; 5: hole; 6: groove, 7: window support block; 8: window material; 9: first adhesive.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

All of the features disclosed in this specification, in addition to mutually exclusive features and/or steps, may be combined in any form.

The present invention is described in detail with accompanying drawings as follows.

First Embodiment

A preparation method of a split-window CMP (chemical mechanical polishing) polishing pad comprises steps of:

(S1) preparing a backing 1 and engraving a groove 6 on the backing 1;

(S2) preparing a substrate 4 and coating a layer of first adhesive 9 on a bottom of the substrate 4;

(S3) engraving a window portion 2 on the backing 1 engraved with the groove 6 for accommodating a formed window material 8, wherein the window portion 2 defines a window;

(S4) attaching the backing 1 engraved with the window portion 2 to the substrate 4 coated with the layer of the first adhesive 9 through a layer of second adhesive 3, forming a hole 5 in the substrate 4 corresponding to the window of the backing 1 by punching through a substrate punching mold, and simultaneously forming two window support blocks 7 at two sides of a bottom of the window portion 2, respectively, wherein the layer of first adhesive and the layer of second adhesive are respectively coated on the bottom and a top of the substrate;

(S5) punching an original window material through a punching machine and a window punching mold, and obtaining the formed window material 8;

(S6) coating a layer of primer on the two window support blocks 7; and

(S7) placing the formed window material 8 into the window portion 2, attaching the formed window material 8 to the window support blocks 7, and obtaining the CMP polishing pad.

Preferably, the window portion 2 is oval with a long side of 35 mm, an arc radius of 8.6 mm, and a distance between a center of the window portion and a center of the backing 1 of 98.5 mm.

Preferably, the substrate punching mold is oval, wherein a diameter of the hole is 2.7 mm smaller than a window size of the window portion 2.

Preferably, a size of the window punching mold is as same as that of the window portion 2.

Preferably, the primer is Primer 94.

A CMP (chemical mechanical polishing) polishing pad comprises a backing 1, a substrate 4, a first adhesive 9 and a second adhesive 3, wherein: multiple grooves 6 are provided on the backing 1, the backing 1 comprises a window portion 2 which defines a window, the substrate 4 has a hole 5, a window material 8 is accommodated within the window portion 2, and two window support blocks 7 are respectively located at two sides of a bottom of the window portion 2.

Preferably, both the window and the hole 5 have a same hole center, and a diameter of the hole 5 is smaller than that of the window.

Preferably, the diameter of the hole 5 is 2.7 mm smaller than that of the window.

Preferably, the two window support blocks 7 are centrally symmetrically distributed to each other relatively to the window and the hole 5.

Second Embodiment

A preparation method of a split-window CMP (chemical mechanical polishing) polishing pad comprises steps of:

(S1) preparing a backing 1 and engraving a groove 6 on the backing 1;

(S2) preparing a substrate 4 and coating a layer of first adhesive 9 on a bottom of the substrate 4;

(S3) engraving a window portion 2 on the backing 1 engraved with the groove 6 for accommodating a formed window material 8, wherein the window portion 2 defines a window;

(S4) attaching the backing 1 engraved with the window portion 2 to the substrate 4 coated with the layer of the first adhesive 9 through a layer of second adhesive 3, forming a hole 5 in the substrate 4 corresponding to the window of the backing 1 by punching through a substrate punching mold, and simultaneously forming two window support blocks 7 at two sides of a bottom of the window portion 2, respectively, wherein the layer of first adhesive and the layer of second adhesive are respectively coated on the bottom and a top of the substrate;

(S5) punching an original window material through a punching machine and a window punching mold, and obtaining the formed window material 8;

(S6) coating a layer of primer on the two window support blocks 7; and

(S7) placing the formed window material 8 into the window portion 2, attaching the formed window material 8 to the window support blocks 7, and obtaining the CMP polishing pad.

Preferably, the window portion 2 is oval with a long side of 38 mm, an arc radius of 9.5 mm, and a distance between a center of the window portion and a center of the backing 1 of 101.5 mm.

Preferably, the substrate punching mold is oval, wherein a diameter of the hole is 3.0 mm smaller than a window size of the window portion 2.

Preferably, a size of the window punching mold is as same as that of the window portion 2.

Preferably, the primer is Primer 94.

A CMP (chemical mechanical polishing) polishing pad comprises a backing 1, a substrate 4, a first adhesive 9 and a second adhesive 3, wherein: multiple grooves 6 are provided on the backing 1, the backing 1 comprises a window portion 2 which defines a window, the substrate 4 has a hole 5, a window material 8 is accommodated within the window portion 2, and two window support blocks 7 are respectively located at two sides of a bottom of the window portion 2.

Preferably, both the window and the hole 5 have a same hole center, and a diameter of the hole 5 is smaller than that of the window.

Preferably, the diameter of the hole 5 is 3.0 mm smaller than that of the window.

Preferably, the two window support blocks 7 are centrally symmetrically distributed to each other relatively to the window and the hole 5.

Third Embodiment

A preparation method of a split-window CMP (chemical mechanical polishing) polishing pad comprises steps of:

(S1) preparing a backing 1 and engraving a groove 6 on the backing 1;

(S2) preparing a substrate 4 and coating a layer of first adhesive 9 on a bottom of the substrate 4;

(S3) engraving a window portion 2 on the backing 1 engraved with the groove 6 for accommodating a formed window material 8, wherein the window portion 2 defines a window;

(S4) attaching the backing 1 engraved with the window portion 2 to the substrate 4 coated with the layer of the first adhesive 9 through a layer of second adhesive 3, forming a hole 5 in the substrate 4 corresponding to the window of the backing 1 by punching through a substrate punching mold, and simultaneously forming two window support blocks 7 at two sides of a bottom of the window portion 2, respectively, wherein the layer of first adhesive and the layer of second adhesive are respectively coated on the bottom and a top of the substrate;

(S5) punching an original window material through a punching machine and a window punching mold, and obtaining the formed window material 8;

(S6) coating a layer of primer on the two window support blocks 7, and

(S7) placing the formed window material 8 into the window portion 2, attaching the formed window material 8 to the window support blocks 7, and obtaining the CMP polishing pad.

Preferably, the window portion 2 is oval with a long side of 41 mm, an arc radius of 10.6 mm, and a distance between a center of the window portion and a center of the backing 1 of 104.5 mm.

Preferably, the substrate punching mold is oval, wherein a diameter of the hole is 3.3 mm smaller than a window size of the window portion 2.

Preferably, a size of the window punching mold is as same as that of the window portion 2.

Preferably, the primer is Primer 94.

A CMP (chemical mechanical polishing) polishing pad comprises a backing 1, a substrate 4, a first adhesive 9 and a second adhesive 3, wherein: multiple grooves 6 are provided on the backing 1, the backing 1 comprises a window portion 2 which defines a window, the substrate 4 has a hole 5, a window material 8 is accommodated within the window portion 2, and two window support blocks 7 are respectively located at two sides of a bottom of the window portion 2.

Preferably, both the window and the hole 5 have a same hole center, and a diameter of the hole 5 is smaller than that of the window.

Preferably, the diameter of the hole 5 is 3.3 mm smaller than that of the window.

Preferably, the two window support blocks 7 are centrally symmetrically distributed to each other relatively to the window and the hole 5.

In order to further illustrate the technical effects of the present invention, two types of backings are respectively prepared by two different preparation methods, namely, the split-window and the integrated window, based on the same batch of raw materials provided by the present invention, and then the two backings are respectively sampled and tested. The tensile strength stability and the density uniformity of the backing are tested, and the scrap rate of the backing during processing is recorded. Test data and comparing results are shown in FIGS. 4 to 6.

It can be seen from the above test results that within a certain tensile strength range, the split-window backing has less tensile strength fluctuation and more stable tensile strength than the integrated-window backing; within a certain density range, the split-window backing has less density fluctuation and more uniform density than the integrated-window backing. Moreover, the split-window backing has a lower scrap rate during processing. 

What is claimed is:
 1. A preparation method of a split-window CMP (chemical mechanical polishing) polishing pad comprising steps of: (S1) preparing a backing and engraving a groove on the backing; (S2) preparing a substrate and coating a layer of first adhesive on a bottom of the substrate; (S3) engraving a window portion on the backing engraved with the groove for accommodating a formed window material, wherein the window portion defines a window; (S4) attaching the backing engraved with the window portion to the substrate coated with the layer of the first adhesive through a layer of second adhesive, forming a hole in the substrate corresponding to the window of the backing by punching through a substrate punching mold, and simultaneously forming two window support blocks at two sides of a bottom of the window portion, respectively, wherein the layer of first adhesive and the layer of second adhesive are respectively coated on the bottom and a top of the substrate; (S5) punching an original window material through a punching machine and a window punching mold, and obtaining the formed window material; (S6) coating a layer of primer on the two window support blocks; and (S7) placing the formed window material into the window portion, attaching the formed window material to the window support blocks, and obtaining the CMP polishing pad.
 2. The preparation method, as recited in claim 1, wherein: the window portion is oval with a long side in a range of 35 to 41 mm, an arc radius in a range of 8.6 to 10.6 mm, and a distance between a center of the window portion and a center of the backing in a range of 98.5 to 104.5 mm.
 3. The preparation method, as recited in claim 2, wherein: the window portion has the long side of 38 mm, the arc radius of 9.5 mm, and the distance between the center of the window portion and the center of the backing of 101.5 mm.
 4. The preparation method, as recited in claim 1, wherein: the substrate punching mold is oval, wherein a diameter of the hole is 2.7-3.3 mm smaller than a window size of the window portion.
 5. The preparation method, as recited in claim 1, wherein: a size of the window punching mold is as same as that of the window portion.
 6. The preparation method, as recited in claim 1, wherein: the primer is Primer
 94. 7. A CMP (chemical mechanical polishing) polishing pad, which comprises a backing, a substrate, a first adhesive and a second adhesive, wherein: multiple grooves are provided on the backing, the backing comprises a window portion which defines a window, the substrate has a hole, a window material is accommodated within the window portion, and two window support blocks are respectively located at two sides of a bottom of the window portion.
 8. The CMP polishing pad, as recited in claim 7, wherein: both the window and the hole have a same hole center, and a diameter of the hole is smaller than that of the window.
 9. The CMP polishing pad, as recited in claim 8, wherein: the diameter of the hole is 2.7-3.3 mm smaller than that of the window.
 10. The CMP polishing pad, as recited in claim 7, wherein: the two window support blocks are centrally symmetrically distributed to each other relatively to the window and the hole. 